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1.
Elizabeth Chacko 《GeoJournal》2007,68(2-3):131-140
This paper assesses the mutual impact of returning Indian-origin skilled workers on the cities of Bangalore (Bengaluru) and Hyderabad, which have emerged as India’s leading “tech cities”. During the 1970s and 1980s, there was concern that India was losing its educated workforce to the West, particularly to the United States through a phenomenon known as “brain drain”. More recently, there is evidence that reverse brain drain is occurring, as U.S.-trained Indian professionals are returning to their home country in increasing numbers to take advantage of new growth and employment opportunities. The effects of this skilled, transnationally active labor force on various sectors of the economy, on the social and physical infrastructure of Bangalore and Hyderabad and in forging and solidifying transnational linkages between India and the United States are explored in this paper. This study also investigates the reasons why successful US professionals of Asian-Indian origin are returning to their home country via a series of personal interviews. The paper offers Bangalore and Hyderabad as “worldwide leading cities” with a niche status in the global Information Technology (IT) sector.  相似文献   

2.
Ewald’s recent genealogy of constructions of risk in Western societies argues that the 1980s saw an important paradigm shift to the “precautionary principle”. Critical scholars have taken up this idea as a lens through which to interpret the Bush administration’s ‘war on terror’. I argue that 11 September 2001 actually brought about qualitative changes to this paradigm. Bush’s pre-emptive doctrine is driven, and perhaps even more importantly, continually justified to the US population, by what might be called the “trans-precautionary principle”, a move from “decisionism” to “actionism”, and a new radicalization of the way fear is produced and managed. Donald Rumsfeld’s famous typology of different articulations of knowledge and ignorance offers an excellent analytical window onto the connections between ignorance, fear and geopolitical action in this new regime. In the latter part of the essay, his four modes of knowledge/ignorance are arrayed, for heuristic purposes, in an abstract spatial grid organized along dimensions of the specificity and possession of knowledge. This allows a ‘mapping’ of some of the Bush administration’s more controversial strategies in the ‘war on terror’, as a set of different pathways through Rumsfeld Space.  相似文献   

3.
There is growing recognition among political ecologists of the need to examine shifting natural resource regimes and their effects on livelihoods in “First World” places. This emerging literature has variously examined the “Third World within,” the persistence of “subsistence activities” in the “First World,” and the “reterritorialization” of land tenure and access. However, much of this work has tended to focus on traditional extractive industries in the American West, indigenous claims to lands and resources in the U.S. and Canada, and non-timber resources on public lands. In contrast, we use a case study of African-American sweetgrass basket-makers, associated with the Gullah culture, in South Carolina’s lowcountry to examine the ways in which ongoing amenity-driven residential development is fundamentally reshaping resource access on private lands. Historically, basket-makers harvested the materials (primarily sweetgrass or Mulenbergia filipes) needed for their culturally important art form from accessible, rural, and privately held tracts of land in close proximity to their communities, but development pressures and changes in resident interpretation of property rights has decreased access to basket-making resources. The case is particularly illuminating, as it examines the emergence of ‘conservation subdivisions’ in the region and raises important questions about what “rural uses” and users are being conserved through responses to exurban, suburban, and urban development in formerly rural areas.  相似文献   

4.
Joseph Palis 《GeoJournal》2009,74(3):227-234
My paper aims to ask what space characterizes the various constructs of orientalism and othering in the early short films of Thomas Edison. Using Lefebvre’s concept that social space “subsumes things produced, and encompasses their interrelationships in their coexistence and simultaneity” in these early shorts, I will look at three Biograph actualities found at the Library of Congress-American Memory page to show how space is manifested and negotiated onscreen. I will examine Edison’s “Filipinos Retreat From Trenches”, “Capture of Trenches at Candaba” and “U.S. Troops and Red Cross in the Trenches Before Caloocan” which were all released in 1899. These reenacted short films were shot during the tumultuous years of the Spanish-American War. In the Biograph shorts, the privileged positions of both Spanish and American forces in relation to the annexation of a foreign land in world history books is indicative of the tendency to de-emphasize the contribution of the native population in the war. Manthia Diawara has said that “space is related to power and powerlessness, insofar as those who occupy the center of the screen are usually more powerful than those in the background or completely absent from the screen.” The spatial hierarchies and spatially situated images in Edison’s short films show how historically configured power relations encrypted oppression to its external “others” through the cinematic apparatus.
Joseph PalisEmail:
  相似文献   

5.
Records of very damaging snowstorms, those causing more than $25 million in property losses, across the United States were assessed to define the spatial and temporal dimensions of the nation’s snowstorm activity during 1949–2000. In this 52-year period 155 snowstorms occurred and caused losses totaling $21.6 billion (2000 dollars). The northeastern U.S. had the nation’s maximum storm occurrences (79 storms), total losses ($7.3 billion), and storm intensity. Two-thirds of all U.S. losses occurred in the Northeast, Southeast, and Central climate regions, and storm occurrences and losses were least in the western U.S. The incidence of storms peaked in the 1976–1985 period and exhibited no up or down trend during 1949–2000. However, national losses had a significant upward time trend, as did storm sizes and intensity. States with the greatest number of storms were New York (62) and Pennsylvania (58) with only 2 storms in Montana, Idaho, and Utah. Storm losses in the northeastern and southeastern U.S. had U-shaped time distributions with flat time trends for 1949–2000, but losses in the western regions and Deep South had distinct upward trends in losses and storm size. More than 90% of all storm losses in the western U.S. occurred after 1980. These findings indicating increased losses over time reflect that a rapidly growing population and vulnerability of more property at risk have been major factors affecting losses, and the lack of a change over time in snowstorm incidences suggests no change in climate during 1949–2000.  相似文献   

6.
The sediment-hosted disseminated gold deposits in the Oinling region are of sedimentation-slight-metamorphic origin superimposed by hydrothermal reworking at moderate-low temperatures and are well comparable with the typical Carlin gold deposits in the United States.In view of the confusing concept concerning the “sediment-hosted”and “Carlin-type” gold deposits,the authors propose that the term“sediment-hosted gold deposit”should be used in a broad sense which encompasses at least the four subtypes,i.e.,the Carlin type,the metamorphic fine clastic type,the hydrothermal sedimentary type and the vein type.In oter words,the “Carlin-type”should not be used as a synonym for “sediment-hosted”but is recommended as a subtype under the general category of “sediment-hosted gold deposits”  相似文献   

7.
Joy K. Adams 《GeoJournal》2010,75(3):303-314
Sustained migration of Hispanics and Anglos into Texas’s historical “German belt” has contributed to a significant decline in the proportion of Central Texans claiming German ancestry. Under these circumstances, ethnic festivals are playing an increasingly important role in maintaining the German-American identity of many of the region’s people and places. Organizers and participants frequently tout the events’ inclusiveness, claiming that anyone can temporarily cross ethnic boundaries to become “German for a day” within the festival context. However, participant observation and surveys of festival participants in three historically German-American communities (Brenham, Fredericksburg, and New Braunfels) suggest that ethnic-themed events mirror processes of racialization that have persisted in the region for more than 150 years. In this paper, I argue that, in helping to construct “German” identities for the region’s people and places, German-themed events in Central Texas are implicitly involved in the construction of “non-German” and, by extension “non-white,” ethnic identities. Further, event participation patterns reflect a long-standing black-white racial dichotomy in the region. Within this ethnoracial hierarchy, Hispanics have long occupied a liminal status that is reflected by their involvement in the production and consumption of German-themed events. I contend that Hispanics’ participation in German heritage festivals reflects not only a historical process of “whitening” their racial status but their increasing presence and power within the region.  相似文献   

8.
For many migrants from Latin America, “Hispanic/Latino(a)” is an identity that they encounter in the United States with which they were unfamiliar in their home countries and must negotiate in their everyday lives in a new context. Specifically, immigrants from Central America are unlikely to see themselves as “Hispanic” or “Latino(a)” prior to living in the United States, more often identifying with their home country, city, town, village, or neighborhood. This paper draws on racialization theory and twenty-seven in-depth interviews with Central American immigrants in Atlanta, GA to examine this process of identity negotiation across the traditionally black/white racialized landscapes of a “New South” city. Interview participants adopt a racialized Hispanic identity through a complex process involving the interplay between how they think of themselves and their perceptions of how native-born Atlantans view them. The interview analysis presented herein demonstrates that although Central American immigrants actively negotiate a Hispanic racialized moniker, they do so within an urban context dominated by native-born residents whose racialized assumptions lump Spanish-speaking, brown skinned individuals into a monolithic “Mexican” category. Thus the ways in which racialized difference is constructed in contemporary Atlanta for recent Central American immigrants is very much bound up in such false presumptions of national identity and cultural group belonging.  相似文献   

9.
Located in the Mid-Atlas (Morocco), the Oulmes plateau is famous for its mineral water springs “Sidi Ali” and “Lalla Haya” commercialised by the company “Les Eaux minérales d’Oulmès S.A”. Additionally, groundwater of the Oulmes plateau is intensively exploited for irrigation. The objective of this study, essentially performed from data collected during isotopic (summer 2004) and piezometric and hydrogeochemical field campaigns (spring 2007), is to improve the understanding of the Oulmes hydrogeological system. Analyses and interpretation of these data lead to the statement that this system is constituted by a main deep aquifer of large extension and by minor aquifers in a perched position. However, these aquifers interact enough to be in total equilibrium during the cold and wet period. As highlighted by isotopes, the origin of groundwater is mainly infiltration water except a small part of old groundwater with dissolved gas rising up from the granite through the schists.  相似文献   

10.
Most U.S. metropolitan regions have experienced urban “sprawl,” or the outward spreading of urban development from city centers. For cities lying in areas prone to severe weather, the sprawl phenomenon exposes greater numbers of developed areas and inhabitants to a variety of thunderstorm hazards. This study’s principal goal is to determine how urbanization growth patterns affect a region’s vulnerability to severe weather events. To assess how sprawl may impact vulnerability to tornadoes, hail, and convective wind events, an analysis examining potential loss may be utilized. This study employs two distinct approaches to examine how the Atlanta area’s rapid and extensive development during the latter half of the twentieth Century has affected its overall potential exposure to thunderstorm hazards. First, archived census data are used to estimate overall impacts from hypothetical significant tornado, nontornadic convective wind, and hail events occurring at different time periods throughout several locations in the Atlanta metropolitan region. Second, economic factors are integrated into the analysis, which assists in determining how these hypothetical severe event scenarios may have changed from a cost standpoint if they were to occur in 2006 as opposed to 1960.  相似文献   

11.
During the late Early Cretaceous, the shallow-water domains of the western Tethys are characterized by the widespread deposition of Urgonian-type carbonates rich in rudists, corals and other oligotrophic, shallow-marine organisms. In the Helvetic Alps, the Urgonian occurrences have been dated by ammonite biostratigraphy as Late Barremian and Early Aptian. For the more proximal occurrences in the western Swiss Jura, a recent age model based on bio-, chemo- and sequence stratigraphy has been proposed, which allows for an improved correlation with the Helvetic counterparts. In order to corroborate the recently proposed age model for the Jura, a set of well-preserved rhynchonellids collected from five different lithostratigraphical formations and members (“Marnes bleues d’Hauterive”, “Marnes d’Uttins”, basal marly layers within the “Urgonien Jaune”, “Marnes de la Russille”, “Urgonien Blanc”) has been analysed for its strontium–isotope ratios (87Sr/86Sr). In addition, K–Ar dating was performed on well-preserved glauconite grains from two different levels (“Marnes d’Uttins” and a basal layer within the “Urgonien Jaune”). The correlation of the Sr–isotope data set with a belemnite-based, ammonite-calibrated reference curve provides an age model which is coherent with recently published ages based on calcareous nannofossil biostratigraphy and the correlation of trends in chemo- and sequence stratigraphy. K–Ar dating on well-preserved glauconite grains from the “Marnes d’Uttins” and lowermost part of the “Urgonien Jaune” delivered ages of 127.5 ± 2.3 and 130.7 ± 2.6 Ma, respectively. Whereas the age of the glauconitic level near the base of the “Urgonien Jaune” is chronostratigraphically meaningful, the K–Ar age of the “Marnes d’Uttins” appears too young relative to the presently used time scale. This may be related to rejuvenation of the K–Ar chronometer due to post-depositional Ar loss, most likely during hardground formation. The ages obtained here confirm the Late Barremian age for the onset of the Urgonian platform, an age which is conform with ages obtained in the Helvetic Alps and elsewhere along the northern Tethyan margin.  相似文献   

12.
Laguerre  Michel S. 《GeoJournal》2005,64(1):41-49
This paper briefly reviews the sociological literature on the “New” Chinatown phenomenon stressing its structural location vis-à-vis the “Old” Chinatown and the homeland. It defines the New Chinatown as a panethnopolis, that is a global neighborhood with a majority population of Chinese immigrants and of other ethnic groups of mostly Asian descent. It analyzes more particularly the formation, development, and integration of San Francisco’s Richmond District’s New Chinatown into both the city where it is located and the network of transglobal sites to which it belongs. It provides an interpretation of the New Chinatown as a cultural enclave within the context of globalization theory.  相似文献   

13.
This report gives the conceptual approaches to the development of the theory of the formation of natural water composition in view of the primary properties of aquatic ecosystems: the “principle of uncertainty” in the estimation of the conditions, the “continuity” of the changes proceeding, and the “plurality” of water’s natural structure and components (biotic and abiotic), as well as their interaction processes. The importance and features of each of these basical criteria for characterizing the conditions of an aquatic ecosystems are substantiated in theory.  相似文献   

14.
The seasonal variation in the trace metals’ concentrations (Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn) were investigated in surface sediments of the Pandoh Lake. The horizontal distribution of TC, TN, and TP reflects spatial and temporal differences in sedimentary organic production. The chemical sequential extraction of heavy metals was carried out by seven-step fractionation scheme (Leleyter and Probst in Int J Environ Chem 73:109–128, 1999). The significant concentrations of Ni and Cd were associated with “water soluble (Eua)” fraction in the monsoon and winter, respectively, while “exchangeable (Exch)” and “carbonate-bound (Carb)” fractions for Ni and Cd were abundant in winter and summer. The Cd, Cu, and Pb associated with “Exch” fraction in the summer season support their availability on exchange sites due to oxidized nature of surface sediments. Enrichment of Co, Fe, Mn, and Zn in “AFeO” fraction showed poor bioavailability, while Cd, Cu, and Mn in the monsoon, Co in the winter and summer, and Zn in the winter season showed significant “organically bound (Org)” fraction. The ANOVA was significant for chemical fractions of trace elements except “Carb” fraction of Pb and Zn and “CFeO” fraction of Pb. Factor analysis revealed that the “Eua”, “Exch”, and “Carb” fractions together control the metal enrichment of “MnO”, “AFeO”, and “CFeO” fractions in the summer season.  相似文献   

15.
The conventional Cornell’s source-based approach of probabilistic seismic-hazard assessment (PSHA) has been employed all around the world, whilst many studies often rely on the use of computer packages such as FRISK (McGuire FRISK—a computer program for seismic risk analysis. Open-File Report 78-1007, United States Geological Survey, Department of Interior, Washington 1978) and SEISRISK III (Bender and Perkins SEISRISK III—a computer program for seismic hazard estimation, Bulletin 1772. United States Geological Survey, Department of Interior, Washington 1987). A “black-box” syndrome may be resulted if the user of the software does not have another simple and robust PSHA method that can be used to make comparisons. An alternative method for PSHA, namely direct amplitude-based (DAB) approach, has been developed as a heuristic and efficient method enabling users to undertake their own sanity checks on outputs from computer packages. This paper experiments the application of the DAB approach for three cities in China, Iran, and India, respectively, and compares with documented results computed by the source-based approach. Several insights regarding the procedure of conducting PSHA have also been obtained, which could be useful for future seismic-hazard studies.  相似文献   

16.
In this work some examples of “twisting” of the Earth in the geologic past are given: displacement of the northern parts of the global submeridional structures to the west relative to their southern parts; the rotation of the “geodynamic pair” of Siberia-Laurentia in the Proterozoic; sinistral displacement of the Northern Hemisphere relative to the Southern Hemisphere after the collapse of the last Pangaea; the equatorial rotation of the continental plates; oblique orientation of the global network of planetary fracturing; an inclination of the axis of submeridional compression; sinistral “beveling”; the dextral “twisting” of Venus. All these examples confirm the idea of possible sinistral “twisting” of the Earth that has been proposed by many authors. The cause of such “twisting” is unclear, although it is likely connected with the Earth’s rotation around its axis. Some of these examples show that many paleomagnetic reconstructions can be usefully discussed in a tectonophysical aspect. Moreover, in connection with this data, the development of a new scientific field, called “paleomagnetic tectonophysics”, is possible.  相似文献   

17.
Summary ?Results of experimental investigations in the dry system PtS-PdS-NiS at 1100°C, 1000°C, and 900°C are presented. The phases observed at 1100°C are “cooperite” and a melt, at 1000°C “cooperite”, “braggite”, and a melt and at 900°C “cooperite”, “braggite”, “vysotskite”, Ni1−xS, and a melt. At 1100°C the maximum solubility of Ni in ideal, Pd-free “cooperite” is 2.7 atomic per cent and the Pd-content limit in Ni-free “cooperite” is 12.8 atomic per cent. At 1000°C the maximum solubility of Ni in ideal, Pd-free “cooperite” is 3.3 atomic per cent and the Pd-content in Ni-free “cooperite” is 13.7 atomic per cent. The “braggite” composition ranges from Pt0.56Pd0.38Ni0.06S and Pt0.59Pd0.41S in a Ni-saturated and Ni-free environment respectively to Pt0.18Pd0.80Ni0.02S and Pt0.14Pd0.86S respectively. At 900°C the maximum Ni-content in ideal Pd-free “cooperite” is 3.1 atomic per cent and the Pd-limit in Ni-free “cooperite” is 12.5 atomic per cent. The “braggite” composition ranges from Pt0.59Pd0.29Ni0.12S and Pt0.60Pd0.40S for a Ni-saturated and Ni-free environment respectively, to Pd0.91Ni0.09S and PdS respectively. The Ni-content in “braggite” and “vysotskite” increases slightly with increasing Pt/Pd ratios and is higher at 900°C than at 1000°C. Comparison of experimental trends with cooperite, braggite, and vysotskite analyses from the literature implies high temperatures of formation for Pt-Pd-Ni sulphides in placers if Ni-saturation is assumed.
Zusammenfassung ?Synthetischer ,,Cooperit”, ,,Braggit” und “Vysotskit” im System PtS-PdS-NiS bei 1100°C, 1000°C und 900°C Ergebnisse experimenteller Untersuchungen im trockenen System PtS-PdS-NiS bei 1100°C, 1000°C und 900°C werden dargestellt. Bei 1100°C sind die Phasen “Cooperit” und Schmelze, bei 1000°C “Cooperit”, “Braggit” und Schmelze und bei 900°C “Cooperit”, “Braggit”, “Vysotskit”, Ni1−xS und Schmelze stabil. Bei 1100°C ist die maximale L?slichkeit von Ni in idealem, Pd-freiem “Cooperit” 2.7 Atomprozent und der Pd-Gehalt in Ni-freien “Cooperit” liegt bei maximal 12.8 Atomprozent. Bei 1000°C ist die maximale L?slichkeit von Ni in idealem, Pd-freien “Cooperit” 3.3 Atomprozent und der Pd-Gehalt in Ni-freien “Cooperit” liegt bei maximal 13.7 Atomprozent. Die Zusammensetzung des “Braggits” variiert zwischen Pt0.56Pd0.38Ni0.06S und Pt0.18Pd0.80Ni0.02S in einem Ni-ges?ttigtem und zwischen Pt0.59Pd0.41S und Pt0.14Pd0.86S in einem Ni-freien Umfeld. Bei 900°C liegt die maximale L?slichkeit von Ni in idealem Pd-freien “Cooperit” bei 3.1 Atomprozent und der Pd-Gehalt in Ni-freien “Cooperit” liegt bei maximal 12.5 Atomprozent. Die Zusammensetzung des “Braggits” variiert zwischen Pt0.59Pd0.29Ni0.12S und Pd0.89Ni0.08S in einem Ni-ges?ttigten und zwischen Pt0.59Pd0.40S und PdS in einem Ni-freien Umfeld. Der Nickelgehalt in “Braggit” und “Vysotskit” nimmt mit zunehmendem Pt/Pd Verh?ltnis zu und ist bei 900°C h?her als bei 1000°C. Ein Vergleich der experimentellen Trends mit Cooperit, Braggit und Vysotskit Analysen aus der Literatur weist auf eine Hochtemperaturbildung der Pt-Pd-Ni Sulfide in Seifenlagerst?tten hin, wenn man von Nickels?ttigung ausgeht.

Received October 1, 1998;/revised version accepted September 7, 1999  相似文献   

18.
As a first approximation, the Earth is a sphere; as a second approximation, it may be considered an ellipsoid of revolution. The deviations of the actual Earth’s gravity field from the ellipsoidal “normal” field are so small that they can be understood to be linear. The splitting of the Earth’s gravity field into a “normal” and a remaining small “disturbing” field considerably simplifies the problem of its determination. Under the assumption of an ellipsoidal Earth model, high observational accuracy is achievable only if the deviation (deflection of the vertical) of the physical plumb line, to which measurements refer, from the ellipsoidal normal is not ignored. Hence, the determination of the disturbing potential from known deflections of the vertical is a central problem of physical geodesy. In this paper, we propose a new, well-promising method for modelling the disturbing potential locally from the deflections of the vertical. Essential tools are integral formulae on the sphere based on Green’s function with respect to the Beltrami operator. The determination of the disturbing potential from deflections of the vertical is formulated as a multiscale procedure involving scale-dependent regularized versions of the surface gradient of the Green function. The modelling process is based on a multiscale framework by use of locally supported surface curl-free vector wavelets.   相似文献   

19.
The impact of atmospheric circulation fluctuations (Vangengeim’s classification) on the zoobenthos dynamics in the Sea of Azov was studied. The “western” circulation processes lead to zoobenthos biomass decrease, and the opposite pattern was observed when “eastern” circulation processes prevail. A quasiperiodicity with 3–7 to 10–15 year cycles is revealed for the zoobenthos biomass dynamics. These changes are closely connected with the climatically induced increase of the zoobenthos biomass in the Sea of Azov.  相似文献   

20.
The properties of giant radio sources (GRS’s) are considered with the aim of identifying conditions contributing to their formation, using data from the literature, the Sloan Digital Sky Survey (SDSS), and the APM catalog. The optical and radio properties of normal-size radio sources, (≤1 Mpc), are compared. The following conclusions are reached. (1) The fraction of objects with broad emission lines among GRS’s with high-excitation spectra is the same as for isotropic samples of radio sources; in the framework of the “unified scheme,” this testifies to an isotropic distribution of angles between the radio jets of GRS’s and the line of sight, i.e., GRS’s do not represent a population of objects whose radio jets are in the plane of the sky. (2) Giant radio sources do not differ from normal radio sources in the distributions of various asymmetry parameters for their extended radio components; in the unified scheme, the similarity of the asymmetry distributions for giant radio galaxies and giant radio quasars suggests that the origin of the asymmetry of their extended radio components is inhomogeneity of the external conditions. (3) The observed powers of the radio jets of giant and normal radio sources do not differ, making it unlikely that the large sizes of the GRS’s are due to this factor. (4) The richness and character of the environments of giant and normal radio sources do not differ: giant host galaxies are found in both isolated fields and in clusters of up to Abell class 1 in richness. This argues against the idea that a low density of the environment is the only origin of GRS’s. (5) The relatively large fraction of radio sources with two pairs of extended radio components (so-called double-double radio sources) among GRS’s testifies that the lifetimes of GRS’s are approximately an order of magnitude longer than those of normal radio sources.Given the equal spatial densities of nearby (z < 0.1) GRS’s and FR II radio sources with powers P 1.4 MHz > 1025 W/Hz, this indicates that ∼10% of FR II radio sources have lifetimes an order of magnitude longer, and evolve into GRS’s. (6) The small (∼0.1) ratio of the number of known GRS’s to the number of normal FR II radio sources, together with the observed spatial density of GRS’s at z ∼ 0.6, which is an order of magnitude lower than the predicted value, suggests that a considerable number of GRS’s were missed by surveys at z > 0.1, possibly due to observational selection effects because of their relatively low radio powers and radio surface brightnesses. (7) The absence of “double-double” giant quasars suggests that these objects have a shorter activity time scale than GRS’s. In an evolutionary scenario that is an alternative to the unified scheme uniting “radio loud” quasars and radio galaxies, radio quasars evolve with time into radio galaxies, and the observed relative number of radio quasars among the GRS’s (∼10%) can be interpreted as reflecting the existence of a long-lived population of “radio loud” quasars comprising ∼10% of all radio quasars, with such a population of long-lived radio quasars being the parent population for giant radio galaxies.  相似文献   

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